Numerous work-related injury and illness incidents in which people are exposed to hazardous materials occur each year in the United States. Often these exposures are to chemicals such as corrosives (acids and bases), oxidizers and solvents. Most of these types of exposures are addressed through immediate use of emergency drench showers and eyewashes.
In practical use, emergency showers and eyewashes mitigate the harmful effects of exposures to hazardous materials by using significant volumes of water to drench the affected areas of the body, thereby removing the hazardous material contact and limiting further injury.
Over the years, the largest challenge facing industrial plant designers and specifying engineers has been providing ready access to emergency showers and eyewashes. The less time it takes to get to the emergency equipment, the better. So, placement in larger and much more complex plant operations has been a continuing concern. Logically, emergency equipment is best positioned as close to potential accident sites as possible. While this makes perfect sense for the immediate treatment needs (i.e.: flushing away the foreign substance to mitigate further injury), it creates another challenge for those charged with the responsibility of providing further aid.
In simple terms, the safety staff's responsibility for administering both immediate and follow-up aid requires instantaneous notification of any accident event, regardless of its location. In large facilities, this communication imperative is most often addressed through the use of centralized monitoring stations, where telltale devices signal that drench showers or eyewashes have been activated.
Today's plumbed-in safety showers and eyewashes are a far cry from their predecessors. While earlier efforts might have been little more than a bolting together of pipes, valves and shower/eyewash heads, today's state-of-the-art products are engineered packages that operate to exacting standards for pressure, height of flow and diffusion patterns. There's a science to the design and engineering of emergency equipment. And there is also a science to specifying that equipment into an engineered solution that comprehends the equipment's use and the quality, pressure and temperature of the water supplied to that equipment. For instance, the concurrent use of several showers can have a dramatic impact on the available water pressure, to the point where the flow at the showers can fall below ANSI standards. Or, the inlet water might be sufficiently cold or hot enough to the point where the injured worker cannot possibly stand under the shower for the required 15-minute duration.
So, a totally engineered solution is the best bet for covering all possible scenarios in your specific application... totally engineered in all aspects.
Alarm Switches
Activating an alarm to signal that emergency equipment is in operation is critical to assuring the proper follow-up assistance is available, regardless of where in the plant the accident has occurred. From the very early days of emergency equipment design, there have been audible and visual alarms attached to these products, with remote monitoring having been more recently added. Alarm switches used generally fall into three categories:
The Traditional "Drop Switch": The drop switch is, frankly, just that. When the injured individual approaches the emergency shower or eyewash, he/she would simply remove a weight from its holder and drop it, signaling that the equipment was about to be activated. Although drop switches are about the oldest technology currently in use, they still function well. However, because of the fact that they require a separate physical effort to remove and drop the weight, they are generally thought to be a less effective approach.
The "Flow-Switch": Flow switches are one of the most commonly used configurations. A specifically designed paddle is placed inside of the piping near the activation switch. The paddle is attached to an external switch by a rotating shaft. When water begins to flow due to activation of the shower/eyewash, the paddle senses the movement rotating the shaft and throws the switch.
The "Proximity Switch": The proximity switch is another widely used configuration. It is mounted on the outside of the equipment, in an area near the activation mechanism. By secondary attachment to the activation switch, it is thrown concurrently with the activation of the equipment.
The proper switch configuration for an application will depend on specific needs and circumstances.
In early or smaller-scale applications, switches served the important role of local notification through visual and audible alarms of shower/eyewash activation. The advent of centralized monitoring tasked activation switches even further as they were required to notify centralized monitoring resources via hardwired telltale devices. However, as plant configurations grew in size and complexity, hardwiring of centralized alarms has been stretched to the limit in many applications.
The next step in the evolutionary process is wireless monitoring. Potentially using any switch design, wireless technologies couple an RF transmitter with the activation switch to immediately notify centralized monitoring, where the corresponding RF receiver resides. The beauty of the technology is that a single receiver can monitor a large number of transmitters and, unlike most hardwired assets, wireless applications monitor their own total system integrity. Wireless monitoring also mitigates the risk of damage to hardwired assets typically experienced in industrial environments. Finally, wireless technologies save the cost of hardwired installation (up to $50 per foot) and are, obviously, much easier to relocate.
In safety engineering and management today, the issue of developing an engineered solution that comprehends all circumstances, needs, possible use scenarios, available water pressures/volumes/temperatures and available technologies is the wisest choice.
Casey Hayes is the engineering manager at Haws Corp., located in Sparks, Nev. He can be reached at (775) 353-8320 or [email protected]. Haws Corp. designs, manufactures and distributes drinking fountains and emergency equipment.